Field of Invention
The present invention relates to a substance delivery device and a substance delivery device using the same.
Related Art
Oral administration and subcutaneous injection are general and traditional routes for delivering a drug. Oral administration is now a most widely used method to deliver a drug because of its convenience. However, oral administration and subcutaneous injection both have drawbacks.
Oral medications, after swallowed, are digested in the gastrointestinal system and pass through the liver to experience a first-pass metabolism, and emerge from the liver to enter the circulatory system, to such an extent that the remaining medications actually have systemic effect. The whole process not only costs much time, but includes other factors (e.g. digestion) which make it is difficult to control the efficacy of drugs precisely, and even make the drug lose its efficacy. On the other hand, subcutaneous injection of drugs is an invasive treatment which may not only be very painful, but also poses a risk of infection by needle.
Transdermal drug delivery (TDD) has become an attractive route to administer drugs in recent years. It is a route to deliver medications through skin and the medications will be absorbed thereby. The forms of TDD include ointment, oil, patch, gel, and inhalation aerosol. TDD not only avoids the possibility to lose the efficacy of medication resulted from digestion of gastrointestinal system as oral medications do, but also has advantages over subcutaneous injections, which are painful and pose the risk of infection.
However, stratum corneum is the outermost protective layer of skin. It is hydrophobic and negatively charged, which poses particular challenges in delivery of macromolecules and hydrophilic drugs through skin.
In order to overcome the abovementioned difficulties, in recent years, a technique has been developed to combine a traditional needle-injection and a transdermal drug delivery patch, which has been accomplished by covering a patch with microneedles. Microneedles can penetrate the stratum corneum to directly deliver macromolecular drugs and hydrophilic drugs, such as vaccines, proteins, insulin, and deoxyribonucleic acids, to epidermis and dermis. Therefore, drugs will be absorbed through capillaries and then enter into systemic circulation. Transdermal drug delivery with a microneedle patch has advantages over the traditional needle-injection TDD can reduce discomforts significantly and patients may therefore have a higher intention to take vaccination. The microneedle patch is a gospel to those who fear of traditional needle-injection, especially children and even elderly. In addition, a microneedle patch is easy for medical personnel and patients to handle it conveniently.
However, current techniques focus on developing microneedle patches which can release substances, such as vaccines and drugs, in a short-term, and are rapid-release forms. A few sustained-release patches use bio-degradable polymer as the material of microneedles. However, such patches have to be placed on skin for quite a long time to reach a sustained release. It often induces allergic reactions, such as symptoms of itching and skin rashness, and causes patients' discomfort and inconvenience.
Therefore, it is an important subject to provide a substance delivery device and method providing a sustained release without bringing patients discomfort by improving materials, structures and release process.